I was surprised they used a square (5x5) as fonts are usually taller than wide.

But they mention:

> Narrower 4x5 and 3x5 dimensions are possible, but would require sacrificing the M, dotted zero, and reduce U/V/Y distinctiveness

Note whole the characters are 5x5, the character box is 6x6 to provide for Spain between characters, from what I can tell from https://maurycyz.com/projects/mcufont/real.jpg